Vehicle mounted virtual visor system with rate-limited optical state changes

ABSTRACT

A virtual visor system is disclosed that includes a visor having a plurality of independently operable pixels that are selectively operated with a variable opacity. A camera captures images of the face of a driver or other passenger and, based on the captured images, a controller operates the visor to automatically and selectively darken a limited portion thereof to block the sun or other illumination source from striking the eyes of the driver, while leaving the remainder of the visor transparent. The virtual visor system advantageously limits the rate of change of the opacity of each pixel of the visor while updating the optical state of the visor. In this way, rapid and distracting changes in the optical state of the visor are avoided, thereby improving the safety of the vehicle.

FIELD

The device and method disclosed in this document relates to anti-glare systems and, more particularly, to vehicle mounted virtual visor system having rate-limited optical state changes.

BACKGROUND

Unless otherwise indicated herein, the materials described in this section are not admitted to be the prior art by inclusion in this section.

When driving an automotive vehicle while the sun is low on the horizon, such as in the mornings and evenings, a common problem is that the sun shines through the windshield and disrupts the view of the driver, making it challenging to clearly see the road, traffic signals, road signs, and other vehicles. A conventional solution to this problem is to include manually deployable sun visors mounted adjacent to the windshield of the vehicle. A sun visor is typically an opaque object which can be deployed between a passenger and the sun to block direct sunlight from striking the passenger's eyes. Particularly, the sun visor can be flipped, rotated, or otherwise repositioned to cover a portion of the windshield in an effort to block the sun.

However, in the deployed position, the sun visor generally fails to consistently and continuously prevent the sun from disrupting the view of the driver unless it is frequently adjusted. Particularly, due to its large size and distance from the earth, the sun acts as a directional light source. Thus, in order to block the sunlight, the sun visor must be positioned such that it intersects the subset of the sun's rays that would pass through the position of the driver's eyes. The correct positioning of the sun visor varies as a function of the position of the passenger's eyes and the direction of the sunlight relative to the passenger's eyes. During a typical driving trip in a vehicle, the vehicle generally changes directions frequently and the driver will move his or her head within the vehicle frequently. Accordingly, a sun visor must be repositioned or adjusted frequently to ensure continuous blockage of the sunlight.

In an effort to overcome these shortcomings, sun visors are typically much larger than is otherwise necessary to effectively block sunlight, such that a single position of the sun visor can block sunlight with a variety of head positions and sunlight directions, thereby reducing the required frequency of adjusting the sun visor. However, this larger size in turn obstructs the view of the driver, often blocking the view of high mounted road signs and stop lights. In order to overcome these issues, the driver often must reposition his or her head so that the visor blocks the sun, while not overly disrupting the rest of his or her view.

What is needed is a visor system which reliably blocks high intensity light sources, such as the sun, while minimizing distraction of the driver and disruption to the rest of the view of the driver through the windshield.

SUMMARY

A visor system is disclosed. The visor system comprises a camera mounted within an environment and configured to capture a plurality of images of a face of a person in the environment. The visor system further comprises a visor mounted within the environment and having a plurality of pixels arranged contiguously. An optical state of the visor is adjustable by selectively operating each respective pixel of the plurality of pixels with a respective pixel optical state selected from a plurality of pixel optical states. Each pixel optical state in the plurality of pixel optical states has a different opacity such that the respective pixel blocks a different amount of light from passing through a corresponding area of the visor. The visor system further comprises a controller operably connected to the camera and to the visor. The controller is configured to receive the plurality of images from the camera. The controller is configured to, for each respective image in the plurality of images, determine, based on the respective image, an updated optical state for the visor to block a light source from shining through the visor into eyes of the person, a change in opacity of the pixel optical state of each pixel in the plurality of pixels in the updated optical state compared to a current optical state of the visor being limited by a maximum rate of change of opacity. The controller is configured to, for each respective image in the plurality of images, operate the visor to display the updated optical state.

A method for operating a visor system is disclosed. The visor system includes a visor mounted within an environment and having a plurality of pixels arranged contiguously, an optical state of the visor is adjustable by selectively operating each respective pixel of the plurality of pixels with a respective pixel optical state selected from a plurality of pixel optical states. Each pixel optical state in the plurality of pixel optical states has a different opacity such that the respective pixel blocks a different amount of light from passing through a corresponding area of the visor. The method comprises capturing, with a camera mounted within the environment, a plurality of images of a face of a person in the environment. The method further comprises, for each respective image in the plurality of images, determining, with a controller, based on the respective image, an updated optical state for the visor to block a light source from shining through the visor into eyes of the person, a change in opacity of the pixel optical state of each pixel in the plurality of pixels in the updated optical state compared to a current optical state of the visor being limited by a maximum rate of change of opacity. The method further comprises, for each respective image in the plurality of images, displaying, with the visor, the updated optical state.

A non-transitory computer-readable medium for operating a visor system is disclosed. The visor system includes a camera mounted within an environment and configured to capture a plurality of images of a face of a person of the environment. The visor system further includes a visor mounted within the environment and having a plurality of pixels arranged contiguously, an optical state of the visor is adjustable by selectively operating each respective pixel of the plurality of pixels with a respective pixel optical state selected from a plurality of pixel optical states. Each pixel optical state in the plurality of pixel optical states has a different opacity such that the respective pixel blocks a different amount of light from passing through a corresponding area of the visor. The computer-readable medium stores program instructions that, when executed by a processor, cause the processor to receive the plurality of images from the camera. The computer-readable medium further stores program instructions that, when executed by a processor, cause the processor to, for each respective image in the plurality of images, determine, based on the respective image, an updated optical state for the visor to block a light source from shining through the visor into eyes of the person, a change in opacity of the pixel optical state of each pixel in the plurality of pixels in the updated optical state compared to a current optical state of the visor being limited by a maximum rate of change of opacity. The computer-readable medium further stores program instructions that, when executed by a processor, cause the processor to, for each respective image in the plurality of images, operate the visor to display the updated optical state.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and other features of visor system and method are explained in the following description, taken in connection with the accompanying drawings.

FIG. 1 is a side view of a portion of a driver compartment of a vehicle showing an exemplary embodiment of a vehicle mounted virtual visor system.

FIG. 2 shows an exemplary embodiment of the visor of FIG. 1 operated in an exemplary blocking mode.

FIG. 3 shows a portion of an exemplary image of the face of the driver captured by the camera of FIG. 1 .

FIG. 4 shows a method for controlling an optical state of the visor to continuously block sunlight from striking the eyes of the driver or other passenger, while minimizing the visual disturbance of updates to the optical state.

FIG. 5 shows an illustration of the relationships between the current optical state, target optical state, and updated optical state of the visor over three exemplary update cycles.

FIG. 6 shows an exemplary method for determining the most likely current sunlight direction in a probabilistic manner using Bayesian Inference.

FIG. 7 shows a portion of an exemplary image of the face of the driver captured by the camera of FIG. 1 , in which sample points are illustrated.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings and described in the following written specification. It is understood that no limitation to the scope of the disclosure is thereby intended. It is further understood that the present disclosure includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles of the disclosure as would normally occur to one skilled in the art which this disclosure pertains.

Virtual Visor System

With reference to FIG. 1 , an exemplary embodiment of a vehicle mounted virtual visor system 20 is described. Particularly, FIG. 1 shows a partial view of a cabin 17 and windshield 19 of a vehicle 18 in which the virtual visor system 20 is installed. The vehicle 18 may be a passenger vehicle, a commercial vehicle, an off-road vehicle, a recreational vehicle, an airplane, a boat, or any other suitable vehicle. It should be appreciated, however, that the virtual visor system 20 may also be used in environments other than a vehicle, such as a room of a building (e.g., an office environment or manufacturing setting). The virtual visor system 20 at least includes a controller 10, a visor 12, and a camera 14. The visor 12 comprises a plurality of independently operable regions, referred to herein as “pixels,” that can be selectively operated with a variable opacity/transparency. The camera 14 captures images of the face of a driver 16 or other passenger and, based on the captured images, the controller 10 operates the visor 12 to automatically and selectively darken a limited portion thereof to block the sun or other illumination source from striking the eyes of the driver 16, while leaving the remainder of the visor 12 transparent. Thus, the virtual visor system 20 advantageously eliminates unnecessary obstructions to the drivers view while also blocking distracting light sources, thereby improving the safety of the vehicle 18 by minimizing disruption of the view of the driver.

In at least some embodiments, the visor 12 is mounted or otherwise attached to a surface within the cabin 17 of the vehicle 18, in the field of view of the driver 16 or other passenger. Particularly, in some embodiments, the visor 12 is mounted to the vehicle 18 so as to be in the line of sight of the driver 16 sitting in the driver's seat and looking through the windshield 19. For example, in the case of a left-hand drive vehicle, the visor 12 may be mounted to the roof adjacent to the windshield 19 so as to cover and/or obstruct at least a portion of an upper-left (as viewed from within the cabin 17) region of the windshield 19. Conversely, in the case of a right-hand drive vehicle, the visor 12 may be mounted to the roof adjacent to the windshield 19 so as to cover and/or obstruct at least a portion of an upper-right (as viewed from within the cabin 17) region of the windshield 19. The visor 12 may be proportioned, mounted, and arranged to cover and/or obstruct any region or regions of the windshield 19, as well as regions of other windows of the vehicle 18. As further examples, the visor 12 may be mounted to any of the pillars of the vehicle 18 adjacent to the windshield 19 or other window, mounted to the dash, or mounted directly to the windshield 19 other window itself in order to cover different regions of the windshield 19 or other windows of the vehicle 18. In some embodiments, the visor 12 may by hingedly or pivotally mounted to an interior surface of the vehicle 18 such that its orientation can be manually adjusted. Alternatively, in some embodiments, the visor 12 is integrated with the glass of the windshield 19 or other window of the vehicle.

With reference to FIG. 2 , the visor 12 comprises a plurality of independently operable pixels 22 that are contiguously arranged to form a panel. As used herein, the term “pixel” refers to any independently operable portion of a medium that is controllable to adjust an optical transparency thereof. In at least some embodiments, the plurality of pixels 22 are contiguously arranged within a bezel 24. In the illustrated embodiment, the pixels 22 each have a hexagonal shape and are arranged in a uniform grid formation. However, it should be appreciated that the pixels 22 may be of any size and shape and the visor 12 may include non-uniform arrangements of pixels 22 having mixed sizes and shapes. In at least one embodiment, the visor 12 is an LCD panel having LCD pixels 22. However, it should be appreciated that the visor 12 may instead utilize various other technologies in which portions of the visor 12 are electrically, magnetically, or mechanically controllable to adjust an optical transparency thereof.

In order to block sunlight from striking the eyes of the driver 16, a subset of pixels 26 are operated in an at least partially opaque optical state, whereas the remaining pixels 28 are operated in a transparent optical state. The subset of pixels 26 are intended block sunlight from striking the eyes of the driver 16 and may also be referred to herein as the “blocker.” Particularly, each pixel 22 is configured to be selectively operated by the controller 10 in one of a plurality of pixel optical states, at least including: (1) a transparent optical state in which the respective pixel allows light to pass through a respective area of the visor 12 and (2) an opaque optical state in which the respective pixel blocks light from passing through the respective area of the visor 12. In some embodiments, the plurality of pixel optical states that further includes (3) one or more intermediate optical states in which the respective pixel partially blocks different amounts of light from passing through the respective area of the visor 12. It should be appreciated that the “opaque optical state” and a “transparent optical state” do not necessarily indicate a 100% opaque characteristic and a 100% transparent characteristic, respectively. Instead, the opaque optical state is simply an optical state in which the pixel which blocks more light from passing through the respective area than the pixel does in the transparent optical state. Generally, the opaque optical state blocks the most light from passing through the respective area and the transparent optical state blocks the least light from passing through the respective area.

Returning to FIG. 1 , the controller 10 generally comprises at least one processor and at least one associated memory having program instructions stored thereon, which are executed by the at least one processor to achieve the described functionalities. It will be recognized by those of ordinary skill in the art that a “controller” or “processor” includes any hardware system, hardware mechanism or hardware component that processes data, signals, or other information. The controller 10 may include a system with a central processing unit, multiple processing units, or dedicated circuitry for achieving specific functionality.

In at least one embodiment, the controller 10 is operably connected to one or more row/column driver circuits (not shown), via which the controller 10 controls the optical state of each individual pixel of the visor 12. The row/column driver circuits may comprise any suitable arrangement of multiplexers, transistors, amplifiers, capacitors, etc. configured to control the optical state of each individual pixel of the visor 12 in response to control signals provided by the controller 10. In some embodiments, portions of the row/column driver circuits may be integrated with the visor 12 and the pixels thereof. In some embodiments, portions of the row/column driver circuits may be integrated with the controller 10.

With continued reference to FIG. 1 , the camera 14 continuously or periodically captures images of the face of the driver 16 or other passenger in the cabin 17 of the vehicle 18. The camera 14 is mounted in the vehicle 18 at a location which has a clear view of at least part of the face of the driver 16 so as to detect a shadow cast on the face of the driver 16. In the illustrated embodiment, the camera 14 is mounted or otherwise integrated with the roof of the vehicle 18, above the windshield 19 and directly in front of the driver 16. In another embodiment, the camera 14 is mounted to or otherwise integrated with the dash or steering wheel directly in front of the driver 16. In yet another embodiment, the camera 14 integrated with visor 12, such as in the bezel 24. In a further embodiment, the camera 14 is mounted to or otherwise integrated with the left or right “A” pillar of the vehicle 18.

FIG. 3 shows a portion of an exemplary image 50 of the face of the driver 16 or other passenger. As can be seen, a shadow 52 is projected onto the face of the driver 16 or other passenger by the optical state of the visor 12. In particular, the shadow 52 corresponds to a projection of the subset of pixels 26 that are operated in the at least partially opaque optical state. The controller 10 is configured to receive the images of the face of the driver 16 or other passenger from the camera 14 and, based on the images, continuously update the optical state of the visor 12. In particular, the controller 10 determines and continuously updates a sunlight direction based on the location of the detected shadow 52 on the face of the driver 16 or other passenger. Additionally the controller 10 determines and continuously updates positions of the eyes of the driver 16 or other passenger within the cabin 17, based on the images. Based on the sunlight direction and the positions of the eyes of the driver 16 or other passenger, the controller 10 updates the subset of pixels 26 that are operated in the at least partially opaque optical state so that the sunlight continues to be blocked from striking the eyes of the driver 16 or other passenger.

In the example of FIG. 2 , the subset of pixels 26 forms a blocker that is positioned based on the sunlight direction and the positions of the eyes of the driver 16 or other passenger, such that it encompasses the projected eye positions (shown as ‘x’ markings within the blocker) on the visor 12 and the pixels thereof are operated in a most opaque pixel optical state. In this way, the opaque pixels of the blocker block sunlight from passing through the visor 12 and striking the eyes of the driver 16 or other passenger.

It should be appreciated that, both the sunlight direction and the position of the eyes of the driver 16 or other passenger will change frequently, and sometimes rapidly, as the vehicle 18 is driven. Depending on strategy adopted by the controller 10 for determining and updating the optical state of the visor 12, this may result in equally frequent and rapid changes in the optical state of the visor 12. However, frequent and rapid changes in the optical state of the visor 12 create a visual disturbance that can be distracting to the driver 16. Accordingly, it is advantageous for the controller 10 to adopt one or more strategies to minimize the amount and the extent of these visual disturbances.

Method of Operating the Virtual Visor System

A variety of methods and processes are described below for operating the virtual visor system 20. In these descriptions, statements that a method, processor, and/or system is performing some task or function refers to a controller or processor (e.g., the processor of the controller 10) executing program instructions stored in non-transitory computer readable storage media (e.g., the memory of the controller 10) operatively connected to the controller or processor to manipulate data or to operate one or more components in the virtual visor system 20 to perform the task or function. Additionally, the steps of the methods may be performed in any feasible chronological order, regardless of the order shown in the figures or the order in which the steps are described.

FIG. 4 shows a method 100 for controlling an optical state of the visor 12 to continuously block sunlight from striking the eyes of the driver 16 or other passenger, while minimizing the visual disturbance of updates to the optical state. The method 100 advantageously limits the rate of change of the opacity of each pixel of the visor 12 while updating the optical state of the visor. In this way, rapid and distracting changes in the optical state of the visor 12 are avoided.

Although described primarily with respect to blocking sunlight from striking the eyes of the driver 16, it should be appreciated that the method 100 is equally applicable to blocking sunlight from striking the eyes of other passengers in the vehicle 18. Additionally, although described primarily with respect to sunlight, it should be appreciated that the method 100 is equally applicable to blocking light from any other light source, including multiple light sources (e.g., oncoming vehicle headlights).

The method 100 begins with initializing an optical state of the visor (block 110). Particularly, the controller 10 initializes the visor 12 by operating the visor 12 to have a predetermined initial optical state. As used herein, the “optical state” of the visor 12 refers to the collective pixel optical states of all of the pixels 22 of the visor 12. Likewise, as used herein, the “pixel optical state” refers to the operating state of an individual one of the pixels 22 of the visor 12. In at least some embodiments, the optical state of the visor 12 is characterized by an array of integer values in which each integer value indicates a respective pixel optical state O_(i) of a respective pixel i. In embodiments in which the pixels 22 of the visor 12 are arranged in a uniform grid formation having a plurality of m columns and a plurality of n rows, the optical state of the visor 12 is characterized in particular by an [m×n] array of integer values O_(i,j), each representing the pixel optical state of a respective pixel at the location (i,j). In at least one embodiment, the integer values have a value selected from a predetermined range of values (e.g., 0-255) corresponding to a plurality of possible pixel optical states (e.g., where 0 indicates a most transparent pixel optical state, 255 indicates a most opaque pixel optical state, and the intermediate values indicate intermediate opacities therebetween).

In at least some embodiments, the predetermined initial optical state includes at least some pixels 22 in the most opaque pixel optical state or one of the intermediate pixel optical states such that the initial optical state will cast a shadow on the face of the driver 16. The predetermined initial optical state may include a subset of pixels 22 operated in the most opaque optical state that form a cross, a grid, or some other pattern that is optimal for an initial shadow detection on the face of the driver 16. In some embodiments, the controller 10 initializes the visor 12 in response to receiving a control signal from a vehicle computer (not shown) or a driver-operated switch/button indicating that the virtual visor system 20 is to begin operation.

The controller 10 stores the initial optical state a memory of the controller 10 as the current optical state of the visor 12. For clarity, it is noted that the current optical state of the visor 12 refers to the optical state that is currently displayed by the visor 12 and, likewise, the current pixel optical state O_(i,j) ^(current) for each respective pixel 22 refers to the pixel optical state that is currently displayed by the respective pixel 22 the visor 12. Thus, the current optical state for the visor 12 is a collection of current pixel optical states O_(i,j) ^(current) for each pixel 22 of the visor 12. In a first update cycle of the method 100, the current optical state of the visor 12 is the predetermined initial optical state discussed above. In each subsequent update cycle of the method 100, the current optical state of the visor 12 is the most recent updated optical state, discussed below with respect to blocks 170 and 180. As used herein, the phrase “update cycle” refers to a respective iteration of the loop illustrated in FIG. 4 , consisting generally of the blocks 120, 130, 140, 150, 160, 170, and 180, described in detail below.

The method 100 continues with capturing an image of the face of the driver (block 120). Particularly, the camera 14, which is oriented toward the face of the driver 16, captures an image of the face of the driver 16. The controller 10 receives the captured image(s) from the camera 14. In one embodiment, the controller 10 stores the captured image(s) from the camera 14 in the memory of the controller 10. In at least some embodiments, the camera 14 is configured to continuously or periodically capture images of the face of the driver 16 in the form of video and, except for the initialization in block 110, the processes of the method 100 can be repeated for each image frame captured by the camera 14.

The method 100 continues with determining the current pose of the head of the driver and the current eye positions of the driver (block 130). Particularly, based on the image(s) captured by the camera 14, the controller 10 determines a current pose of the head of the driver 16 (i.e., the position and orientation of the head within the cabin 17). The controller 10 stores the current pose of the head of the driver 16 in the memory of the controller 10. The pose of the head of the driver 16 can, for example, be characterized and/or represented by a set of coordinates [X^(head), Y^(head), Z^(head)] defining the position of the head of the driver 16 and a set of angles [θ_(X) ^(head), θ_(Y) ^(head), θ_(Z) ^(head)] defining the orientation of the head of the driver 16.

In at least one embodiment, the controller 10 detects the pose of the head of the driver 16 [X^(head), Y^(head), Z^(head)] and [θ_(X) ^(head), θ_(Y) ^(head), θ_(Z) ^(head)] in the frame using a human pose estimation algorithm. It will be appreciated by those of ordinary skill in the art that a human pose estimation algorithm is generally an algorithm that determines a set of key points or coordinates within the image frame that correspond to key features of a person. As applied to images of a human face and pose detection thereof, these key points will generally include facial landmarks including, for example, eyes, ears, nose, mouth, forehead, chin, and the like. It will be appreciated by those of ordinary skill in the art that wide variety of human pose estimation algorithms exist and that many different human pose estimation algorithms can be suitable adapted to determining the current pose of the head of the driver 16 [X^(head), Y^(head), Z^(head)] and [θ_(X) ^(head), θ_(Y) ^(head), θ_(Z) ^(head)].

Based on the current pose of the head of the driver 16 [X^(head), Y^(head), Z^(head)] and [θ_(X) ^(head), θ_(Y) ^(head), θ_(Z) ^(head)] and/or simply based on the key point detection of the human pose estimation algorithm, the controller 10 determines the current position of the eyes of the driver 16 within the cabin 17. The controller 10 stores the current position of the eyes of the driver 16 in the memory of the controller 10. The current position of the eyes of the driver 16 can, for example, be characterized and/or represented by a set of coordinates [X^(left), Y^(left), Z^(left)] defining the position of the left eye of the driver 16 and a set of coordinates [X^(right), Y^(right), Z^(right)] defining the position of the left eye of the driver 16. As mentioned above, the position of the eyes of the driver 16 within the cabin 17 are one of the two parameters required to determine the necessary optical state of the visor 12 to block sunlight from striking the eyes of the driver 16.

The method 100 continues with determining a current sunlight direction (block 140). Particularly, based on the image(s) captured by the camera 14, the controller 10 determines the current sunlight direction. The controller 10 stores the current sunlight direction in the memory of the controller 10. Due to its large size and distance from the earth, the sun essentially acts as a directional light source. Thus, the sunlight direction can be represented by vector that passes through the visor 12 and toward the driver 16. Though, it should be appreciated that some non-parallel sunrays may pass through the visor 12 and, as such, this vector is merely an approximation. This vector can be represented by a pair of angles including the angle at which the sunlight passes through the visor 12 along a first axis (e.g. a horizontal axis) and the angle at which the sunlight passes through the visor 12 along a second axis (e.g., a vertical axis). The current sunlight direction can, for example, can be characterized and/or represented by an angle pair [θ_(X) ^(sun), θ_(Y) ^(sun)], where −90°<θ_(X)<90° is a horizontal angle at which the sunlight passes through the visor 12 and −90°<θ_(Y)<90° is a vertical angle at which the sunlight passes through the visor 12. It should be appreciated that these angles can be defined with respect to a variety of different frames of reference and a sunlight direction [0°, 0° ] may, for example, be normal to the plane/surface of the visor 12, normal to the viewing direction of the camera 14, or normal to the viewing directly of the driver 16. Likewise, the possible ranges for the angle pair [θ_(X) ^(sun), θ_(Y) ^(sun)] can be defined differently depending on the frame of reference.

It should be appreciated that the two-dimensional angle pair [θ_(X) ^(sun), θ_(Y) ^(sun)] is sufficient to characterize and/or represent the current sunlight direction, but that this angle pair is relative to a known normal vector. The current sunlight direction can, of course, be characterized and/or represented in three-dimensional terms by three angles [θ_(X) ^(sun), θ_(Y) ^(sun), θ_(Z) ^(sun)], which may, for example, be in the same reference frame as the previously determined positions of the eyes and/or head of the driver 16. This may be the preferred characterization of the sunlight direction in embodiments in which the physical positioning of visor 12 and/or the camera 14 are adjustable.

The controller 10 can be configured to determine the current sunlight direction [θ_(X) ^(sun), θ_(Y) ^(sun)] using a wide variety of methods, in general by detecting the shadow 52 that is projected onto the face of the driver 16 by the optical state of the visor 12. Particularly, the controller 10 determines the current sunlight direction [θ_(X) ^(sun), θ_(Y) ^(sun)] based on (i) the position of the shadow 52 on the face of the driver 16 in the image(s) captured by the camera 14, (ii) the previously determined current pose of the head of the driver 16 [X^(head), Y^(head), Z^(head)] and [θ_(X) ^(head), θ_(Y) ^(head), θ_(Z) ^(head)], and (iii) a known current pose of the visor 12 (i.e., the position and orientation of the visor 12 within the cabin 17). More particularly, given the current pose of the visor 12 and the current pose of the head of the driver 16 [X^(head), Y^(head), Z^(head)] and [θ_(X) ^(head), θ_(Y) ^(head), θ_(Z) ^(head)], the controller 10 determines the current sunlight direction [θ_(X) ^(sun), θ_(Y) ^(sun)] as that which would project a shadow onto the face of the driver 16 at the position and/or orientation of the detected shadow 52 in the image(s) from the camera 14.

In at least one embodiment, the controller 10 is configured to determine the current sunlight direction [θ_(X) ^(sun), θ_(Y) ^(sun)] in a probabilistic manner by determining a set (e.g., an array) of probabilities corresponding to each of a predefined plurality of possible sunlight directions. In one embodiment, the set of probabilities are continuously updated and refined based on new information, for example using Bayes' Theorem, to arrive at an accurate prediction of the current sunlight direction [θ_(X) ^(sun), θ_(Y) ^(sun)]. One exemplary probabilistic method for determining the most likely current sunlight direction [θ_(X) ^(sun), θ_(Y) ^(sun)] is described in greater detail below with respect to FIG. 6 .

The method 100 continues with determining a target optical state for the visor based on the current sunlight direction and the current eye positions (block 150). Particularly, the controller 10 determines a target optical state for the visor 12 based on the image(s) received from the camera 14. More particularly, in some embodiments, the controller 10 determines the target optical state for the visor 12 based on the current position of the eyes of the driver 16 [X^(left), Y^(left), Z^(left)] and [X^(right), Y^(right), Z^(right)] and the current sunlight direction [θ_(X) ^(sun), θ_(Y) ^(sun)]. The controller 10 stores the target optical state for the visor 12 the memory of the controller 10.

In at least one embodiment, the controller 10 determines at least one position on the visor 12 at which the sun (or other light source) shines through the visor 12 into eyes of the driver 16 or other passenger. More particularly, in at least one embodiment, these positions on the visor 12 are projected eye positions. In at least one embodiment, the controller 10 determines the projected eye positions by projecting the current positions of the eyes [X^(left), Y^(left), Z^(left)] and [X^(right), Y^(right), Z^(right)] of the driver 16 onto the plane/surface of the visor 12 using the current sunlight direction [θ_(X) ^(sun), θ_(Y) ^(sun)]. In the case that the current sunlight direction [θ_(X) ^(sun), θ_(Y) ^(sun)] was determined in a probabilistic manner characterized by a set of probabilities, the controller 10 performs this projection using the sunlight direction having the highest probability value according to the most recently updated set of probabilities.

A two-dimensional coordinate space of the plane/surface of the visor 12 has maximum dimensions equal to the physical dimensions A×B (e.g., 24×8 inches) of the visor 12, where A denotes the horizontal width of the visor 12 and B denotes the vertical height of the visor 12. The projected positions of the eyes of the driver 16 onto the visor 12 can, for example, be characterized and/or represented by a set of coordinates [X_(visor) ^(left), Y_(visor) ^(left)] defining the projected position of the left eye of the driver 16 in the coordinate space of the plane/surface of the visor 12 and a set of coordinates [X_(visor) ^(right), Y_(visor) ^(right)] defining the projected position of the right eye of the driver 16 in the coordinate space of the plane/surface of the visor 12.

Next, the controller 10 determines the target optical state for the visor 12 based on the projected eye positions [X_(visor) ^(left), Y_(visor) ^(left)] and [X_(visor) ^(right), Y_(visor) ^(right)] of the driver 16 such that, if visor 12 was operated to display the target optical state, it would block the sunlight from striking the eyes of the driver 16.

Much like the initialized optical state of the visor 12, the target optical state for the visor 12 is characterized by an array of target pixel optical states O_(i,j) ^(Target) for the pixels 22 of the visor 12, each characterized by an integer value indicating a respective target pixel optical state O_(i,j) ^(Target) of a respective pixel at a location (i,j). In embodiments in which the pixels 22 of the visor 12 are arranged in a uniform grid formation having a plurality of m columns and a plurality of n rows, the target optical state for the visor 12 is characterized in particular by an [m×n] array of integer values. In at least one embodiment, the integer values have a value selected from a predetermined range of values (e.g., 0-255) corresponding to a plurality of possible pixel optical states (e.g., where 0 indicates a most transparent pixel optical state, the intermediate values indicate progressively more opaque opacities pixel optical state, and 255 indicates a most opaque pixel optical state).

The controller 10 may determine the target optical state in accordance with a variety of different blocking modes. As used herein, a “blocking mode” refers to the manner in which the optical state of the visor 12 and/or the pixel optical states of the individual pixels 22 of the visor 12 are determined as a function of the driving conditions of the vehicle 12. As discussed above, the driving conditions of the vehicle 12 are characterized by the sunlight direction [θ_(X) ^(sun), θ_(Y) ^(sun)] and the positions of the eyes [X^(left), Y^(left), Z^(left)] and [X^(right), Y^(right), Z^(right)] of the driver 16 or other passenger or, equivalently, simply characterized by the projected eye positions [X_(visor) ^(left), Y_(visor) ^(left)] and [X_(visor) ^(right), Y_(visor) ^(right)] on the visor 12. Generally, the target optical state comprises a subset of the pixels that is positioned on the visor 12 such that it encompasses the projected eye positions [X_(visor) ^(left), Y_(visor) ^(left)] and [X_(visor) ^(right), Y_(visor) ^(right)] on the visor 12 and, thus, blocks sunlight from passing through the visor 12 and striking the eyes of the driver 16 or other passenger. The pixels in the subset of the pixels are operated in pixel optical states that are sufficiently opaque to block some or all of the sunlight from passing through the visor 12 and striking the eyes of the driver 16.

With reference to FIG. 2 , the subset of pixels 26 illustrate one exemplary blocking mode in which the target optical state includes a roughly rectangular group of pixels 26 positioned such that it encompasses the projected eye positions (shown as ‘x’ markings within the group of pixels 26) on the visor 12 and in which the pixels thereof are operated in a most opaque pixel optical state. In this way, the opaque pixels of the group of pixels 26 block sunlight from passing through the visor 12 and striking the eyes of the driver 16 or other passenger. However, it should be appreciated that a wide variety of blocking modes can be utilized for the target optical state of the visor 12, including strategies that utilize any number of intermediate semi-transparent pixel optical states, in addition to the most opaque pixel optical state.

The controller 10 determines, for each respective pixel 22 of the visor 12, a target pixel optical state O_(i,j) ^(Target) based on a relationship between the position of the respective pixel 22 and the projected eye positions [X_(visor) ^(left), Y_(visor) ^(left)] and [X_(visor) ^(right), Y_(visor) ^(right)] on the visor 12. Particularly, if a respective pixel 22 is positioned relative to the projected eye positions [X_(visor) ^(left), Y_(visor) ^(left)] and [X_(visor) ^(right), Y_(visor) ^(right)] on the visor 12 such that it is located within the group of pixels 26 defined by the blocking mode, the controller 10 determines the target pixel optical state O_(i,j) ^(Target) for the respective pixel 22 as being a predetermined pixel optical state of the group of pixels 26 (e.g., a most opaque pixel optical state). Otherwise, if the respective pixel 22 is positioned relative to the projected eye positions [X_(visor) ^(left), Y_(visor) ^(left)] and [X_(visor) ^(right), Y_(visor) ^(right)] on the visor 12 such that it is not located within the group of pixels 26 defined by the blocking mode, then the controller 10 determines the target pixel optical state O_(i,j) ^(Target) for the respective pixel 22 as a predetermined ‘transparent’ pixel optical state (e.g., the least opaque pixel optical state).

The method 100 continues with comparing each pixel of a current optical state of the visor with each pixel of the target optical state (block 160). Particularly, the controller 10 compares between the current optical state of the visor 12 and the target optical state for the visor 12. More particularly, in at least one embodiment, the controller 10 compares the pixel optical state of each pixel of a current optical state of the visor 12 with the pixel optical state of each pixel in the target optical state for the visor 12. In particular, for respective each pixel 22 of the visor 12, the controller 10 determines a difference in opacity between (i) a current pixel optical state O_(i,j) ^(Current) of the respective pixel in the current optical state of the visor 12 and (ii) the target pixel optical state O_(i,j) ^(Target) of the respective pixel in the current optical state of the visor 12. The controller 10 stores the difference in opacity for each pixel 22 in the memory of the controller 10.

The “difference” in opacity between the current pixel optical state O_(i,j) ^(Current) and the target pixel optical state O_(i,j) ^(Target) for a particular pixel 22 can be represented in a variety of ways. As discussed above, the target optical state for the visor 12, as well as the current optical state of the visor 12, may be characterized by an array of integer values in which each integer value indicates a respective current pixel optical state O_(i,j) ^(Current) of a respective pixel at a location (i,j). In at least some embodiments, the integer values representing each pixel optical state in the plurality of possible pixel optical states are ordered according to their respective opacities (e.g., where 0 indicates a most transparent pixel optical state, the intermediate values indicate progressively more opaque opacities pixel optical state, and 255 indicates a most opaque pixel optical state). In such embodiments, the difference in opacity between the current pixel optical state O_(i,j) ^(Current) and the target pixel optical state O_(i,j) ^(Target) for a particular pixel 22 can be represented by a simple subtraction of the integer value representing the current pixel optical state O_(i,j) ^(Current) from the integer value representing the target pixel optical state O_(i,j) ^(Target).

Alternatively, in other embodiments, each of the plurality of possible pixel optical states can be associated with a numerical opacity value. The difference in opacity between the current pixel optical state O_(i,j) ^(Current) and the target pixel optical state O_(i,j) ^(Target) for a particular pixel 22 can be represented by a simple subtraction of the numerical opacity value of current pixel optical state O_(i,j) ^(Current) from the numerical opacity value of the target pixel optical state O_(i,j) ^(Target) for a particular pixel 22. In any case, it should be appreciated that the difference in opacity can be different for each particular pixel 22 and, moreover, that the difference in opacity for each pixel 22 can be positive (e.g., indicating a rising opacity) or negative (e.g., indicating a falling opacity).

The method 100 continues with determining an updated optical state for the visor by adjusting the opacity of each pixel toward that of the target optical state, while limiting the change in opacity of each pixel to a maximum rate of change (block 170). Particularly, the controller 10 determines an updated optical state for the visor 12 based on the image(s) received from the camera 14. In some embodiments, the controller 10 determines the updated optical state for the visor 12 based on the current position of the eyes of the driver 16 [X^(left), Y^(left), Z^(left)] and [X^(right), Y^(right), Z^(right)] sunlight direction [θ_(X) ^(sun), θ_(Y) ^(sun)]. In some embodiments, the controller 10 determines the updated optical state for the visor 12 based on the comparison between the current optical state of the visor 12 and the target optical state for the visor 12 or, more particularly, based on differences in opacity for each pixel 22 between the current optical state and the target optical state.

In any case, the controller 10 determines updated optical state for the visor 12 such that a change in opacity of each individual pixel 22 does not exceed a maximum rate of change of opacity

$\frac{\Delta}{\Delta t}O_{Max}$ e.g., defined in terms or opacity levels per second, or similar). It should be appreciated that, as used herein, “maximum rate of change of opacity” is a maximum magnitude (or absolute value) of the rate of change of opacity and does not have a polarity. Thus, the rate of change of opacity is limited by the maximum rate of change of opacity with respect to positive changes in opacity (i.e., darkening) and with respect to negative changes in opacity (i.e., lightening).

In at least one embodiment, the controller 10 determines an updated optical state for the visor 12 by adjusting and/or modifying the current optical state of the visor 12 toward that of the target optical state for the visor 12, while limiting the change in opacity of each individual pixel 22 to the maximum rate of change of opacity

$\frac{\Delta}{\Delta t}{O_{Max}.}$ The controller 10 stores the updated optical state for the visor 12 in the memory of the controller 10. Much like current optical state of the visor 12 and the target optical state for the visor 12, the updated optical state for the visor 12 is an array of updated pixel optical states O_(i,j) ^(Update) for each pixel 22 of the visor 12. In determining the updated optical state for the visor 12, the controller 10 determines the updated pixel optical state O_(i,j) ^(Update) for each pixel 22, in each case, depending on the respective difference in opacity between the current pixel optical state O_(i,j) ^(Current) and the target pixel optical state O_(i,j) ^(Target) for the respective pixel 22, while limiting the change in opacity of the respective pixel 22 to the maximum rate of change of opacity

$\frac{\Delta}{\Delta t}{O_{Max}.}$

More particularly, if the respective difference in opacity between the current pixel optical state O_(i,j) ^(Current) and the target pixel optical state O_(i,j) ^(Target) for the respective pixel 22 is equal to zero, then the controller 10 determines the updated pixel optical state O_(i,j) ^(Update) for the respective pixel 22 as being equal to the current pixel optical state O_(i,j) ^(Current) of the respective pixel 22 (or equivalently equal to the target pixel optical state O_(i,j) ^(Target) for the respective pixel 22). In other words, the updated pixel optical state O_(i,j) ^(Update) for a respective pixel 22 is unchanged if the current pixel state O_(i,j) ^(Current) is the same as the target pixel optical state O_(i,j) ^(Target).

If an absolute value of the respective difference in opacity between the current pixel optical state O_(i,j) ^(Current) and the target pixel optical state O_(i,j) ^(Target) for the respective pixel 22 is less than a maximum change in opacity ΔO_(Max) for the particular update cycle, then the controller 10 determines the updated pixel optical state O_(i,j) ^(Update) for the respective pixel 22 pixel as being equal to the target pixel optical state O_(i,j) ^(Target) for the respective pixel 22. In other words, the updated pixel optical state O_(i,j) ^(Update) for a respective pixel 22 is set to the target pixel optical state O_(i,j) ^(Target) if it would not violate the maximum rate of change of opacity

$\frac{\Delta}{\Delta t}{O_{Max}.}$

To this end, the controller 10 determines the maximum change in opacity ΔO_(Max) for the particular update cycle by multiplying the maximum rate of change of opacity

$\frac{\Delta}{\Delta t}O_{Max}$ by the amount of time since the most recent update cycle (i.e., the last time an updated optical state for the visor 12 was determined). If the update cycles occurred in a rigidly periodic manner, then the maximum change in opacity ΔO_(Max) for any particular update cycle is always the same. In this case, the maximum rate of change of opacity

$\frac{\Delta}{\Delta t}O_{Max}$ can also be defined in terms of a maximum change in opacity ΔO_(Max) per update cycle. It should be appreciated that, as used herein, “maximum change in opacity” is a maximum magnitude (or absolute value) of change of opacity and does not have a polarity. Thus, the change in opacity is limited by the maximum change in opacity with respect to positive changes in opacity (i.e., darkening) and with respect to negative changes in opacity (i.e., lightening).

Finally, if an absolute value of the respective difference in opacity between the current pixel optical state O_(i,j) ^(Current) and the target pixel optical state O_(i,j) ^(Target) for the respective pixel 22 is greater than the maximum change in opacity ΔO_(Max) for the particular update cycle, then the controller 10 determines the updated pixel optical state O_(i,j) ^(Update) for the respective pixel 22 pixel by adding (or subtracting) the maximum change in opacity ΔO_(Max) for the particular update cycle to the current pixel optical state O_(i,j) ^(Current) of the respective pixel 22. In other words, the updated pixel optical state O_(i,j) ^(Update) for a respective pixel 22 is set to the target pixel optical state O_(i,j) ^(Target) it would not violate the maximum rate of change of opacity

$\frac{\Delta}{\Delta t}{O_{Max}.}$

FIG. 5 shows an illustration of the relationships between the current optical state, target optical state, and updated optical state of the visor over three exemplary update cycles k, k+1, and k+2. Particularly, in the update cycle k, the current optical state of the visor includes a subset of darkened pixels 202 operated in the most opaque pixel optical state. Due to a change in conditions (e.g., a change in sunlight direction and/or position of the eyes of the driver), the target optical state of the visor includes a subset of darkened pixels 204 operated in the most opaque pixel optical state, which is shifted downward and to the right compared to the subset of pixels 202 in the current optical state.

In the illustrated example, it should be understood that the maximum rate of change of opacity

$\frac{\Delta}{\Delta t}O_{Max}$ is defined such that a pixel cannot transition between most transparent pixel optical state and the most opaque pixel optical state within a single update cycle. Instead, the maximum rate of change of opacity

$\frac{\Delta}{\Delta t}O_{Max}$ is defined such that it takes about three update cycles for a pixel to transition between most transparent pixel optical state and the most opaque pixel optical state in a single update cycle. However, this is merely for illustrative purposes and, generally, update cycle period will be very short and the maximum rate of change of opacity

$\frac{\Delta}{\Delta t}O_{Max}$ will be such that it takes many more update cycles to completely transition. Thus, the driver or other passengers perceive a smoother and less distracting transition between optical states of the visor 12.

As can be seen, the updated optical state of the visor in the cycle k includes a subset of darkening pixels 206 that have transitioned from a most transparent pixel optical state to a first semi-opaque pixel optical state. Likewise, the updated optical state of the visor in the cycle k includes a subset of lightening pixels 208 that have transitioned from a most opaque pixel optical state to a second semi-opaque pixel optical state. Additionally, a subset of darkened pixels 210, which consists of the overlap between the current subset of darkened pixels 202 and the target subset of darkened pixels 204, remain unchanged in the most opaque pixel optical state. Finally, the remaining transparent pixels 212, which consist of the pixels that are excluded from both of the subsets of darkened pixels 202, 204, remain unchanged in the most transparent pixel optical state.

In the update cycle k+1, the current optical state of the visor is the same as the updated optical state in update cycle k. In the absence of further changes in conditions, the target optical state of the visor remains the same as in update cycle k. In the updated optical state of the visor in the cycle k+1, the subset of darkening pixels 206 have further transitioned from the first semi-opaque pixel optical state to a more opaque third semi-opaque pixel optical state. Likewise, in the updated optical state of the visor in the cycle k+1, the subset of lightening pixels 208 have further transitioned from the second semi-opaque pixel optical state to a less opaque fourth semi-opaque pixel optical state.

Finally, in the update cycle k+2, the current optical state of the visor is the same as the updated optical state in update cycle k+1. In the absence of further changes in conditions, the target optical state of the visor remains the same as in update cycle k+1. In the updated optical state of the visor in the cycle k+2, the subset of darkening pixels 206 have further transitioned from the third semi-opaque pixel optical state to the most opaque pixel optical state. Likewise, in the updated optical state of the visor in the cycle k+2, the subset of lightening pixels 208 have further transitioned from the fourth semi-opaque pixel optical state to the most transparent pixel optical state.

The maximum rate of change of opacity

$\frac{\Delta}{\Delta t}O_{Max}$ can be defined in a variety of ways. Particularly, as described above, each pixel 22 of the visor 12 is configured to be selectively operated by the controller 10 in one of a plurality of pixel optical states. The plurality of pixel optical states may be represented by respective the integer values have a value selected from a predetermined range of values (e.g., 0-255) defining the transparency level of the respective pixel optical states (e.g., where 0 indicates a most transparent pixel optical state, 255 indicates a most opaque pixel optical state, and the intermediate values indicate intermediate opacities therebetween). In this case, the maximum rate of change of opacity

$\frac{\Delta}{\Delta t}O_{Max}$ can be conveniently represented as a number of transparency levels per unit of time (e.g., a floating point number of transparency levels per second).

$\frac{\Delta}{\Delta t}O_{Max}^{+}$

In some embodiments, a maximum rate of positive change or opacity (i.e., darkening rate) and a maximum rate of negative change of opacity

$\frac{\Delta}{\Delta t}O_{Max}^{-}$ (i.e., lightening rate) can be separately defined. Thus, in determining the updated optical state for the visor 12, if the difference in opacity between a current pixel optical state O_(i,j) ^(Current) and a target pixel optical state O_(i,j) ^(Target) for a respective pixel 22 is positive, then the controller 10 determines an updated pixel optical state O_(i,j) ^(Update) for the respective pixel 22, while limiting the change in opacity of the respective pixel 22 to the maximum rate of positive change of opacity

$\frac{\Delta}{\Delta t}O_{Max}^{+}$ in the same manner described above. Likewise, if the difference in opacity between the current pixel optical state O_(i,j) ^(Current) and the target pixel optical state O_(i,j) ^(Target) for the respective pixel 22 is negative, then the controller 10 determines the updated pixel optical state O_(i,j) ^(Update) for the respective pixel 22, while limiting the change in opacity of the respective pixel 22 to the maximum rate of negative change of opacity

$\frac{\Delta}{\Delta t}O_{Max}^{-}$ in the same manner described above.

In one embodiment, the maximum rate of positive change of opacity

$\frac{\Delta}{\Delta t}O_{Max}^{+}$ (i.e., darkening rate) is higher (in magnitude or absolute value terms) than the maximum rate of negative change of opacity

$\frac{\Delta}{\Delta t}O_{Max}^{-}$ (i.e., lightening rate). In this way, blocking the sunlight from striking the eyes of the driver 16 is prioritized more than maximizing visibility through the visor 12 immediately after a change in conditions.

In some embodiments, the maximum rate of change of opacity

$\frac{\Delta}{\Delta t}O_{Max}$ can be defined as a function of the location of the respective pixel 22, i.e.,

${{\frac{\Delta}{\Delta t}O_{Max}} = {f\left( {i,j} \right)}},$ where (i,j) indicate the location of the respective pixel 22 within the visor 12. Thus, in determining the updated optical state for the visor 12, the controller 10 determines the respective maximum rate of change of opacity

$\frac{\Delta}{\Delta t}O_{Max}$ for each respective pixel 22 and determines the updated pixel optical state O_(i,j) ^(Update) for the respective pixel 22, while limiting the change in opacity of the respective pixel 22 to the respective maximum rate of change of opacity

$\frac{\Delta}{\Delta t}O_{Max}$ for the respective pixel 22 in the same manner described above. As one example, a relatively higher maximum rate of change of opacity

$\frac{\Delta}{\Delta t}O_{Max}$ can be used for pixels 22 near the center of the visor 12 and a relatively lower maximum rate of change of opacity

$\frac{\Delta}{\Delta t}O_{Max}$ for pixels 22 that are further from the center of the visor 12 (i.e., nearer to the perimeter of the visor 12).

In some embodiments, the maximum rate of change of opacity

$\frac{\Delta}{\Delta t}O_{Max}$ can be defined as a function of one or more of the control inputs to the system, in particular, as a function of one or more of (i) the current position of the head of the driver 16, (ii) a current rate of change of the position of the head of the driver 16, (iii) the current positions of the eyes [X^(left), Y^(left), Z^(left)] and [X^(right), Y^(right), Z^(right)] of the driver 16, (iv) a current rate of change of the positions of the eyes of the driver 16, (v) a current sunlight direction [θ_(X) ^(sun), θ_(Y) ^(sun)], and/or (vi) a current rate of change of the sunlight direction. Thus, in determining the updated optical state for the visor 12, the controller 10 determines the respective maximum rate of change of opacity

$\frac{\Delta}{\Delta t}O_{Max}$ for the respective update cycle and determines the updated pixel optical state O_(i,j) ^(Update) for the respective pixel 22, while limiting the change in opacity of the respective pixel 22 to the respective maximum rate of change of opacity

$\frac{\Delta}{\Delta t}O_{Max}$ for the respective update cycle in the same manner described above. As one example, if the driver 16 makes a very fast head movement, the maximum rate of positive change of opacity

$\frac{\Delta}{\Delta t}O_{Max}^{+}$ (i.e., darkening rate) can be adjusted relatively higher, but maximum rate of negative change of opacity

$\frac{\Delta}{\Delta t}O_{Max}^{-}$ (i.e., lightening rate) can be adjusted relatively lower. In this way, the visor 12 responds quickly to darken and block sunlight from striking the eyes of the driver 16, but if the driver 16 brings his or her head back to the original place quickly, the previously darkened location has not been fully lightened yet.

In some embodiments, the maximum rate of change of opacity

$\frac{\Delta}{\Delta t}O_{Max}$ can be adjusted by the user. Particularly, the controller 10 receives a user input from the driver 16 or another passenger indicating a preference for the maximum rate of change of opacity

$\frac{\Delta}{\Delta t}{O_{Max}.}$ The driver 16 or other passenger can provide the user input via a user interface of the virtual visor system 20 or via user interface of the vehicle 18, such as an infotainment system, that is in communication with the controller 10. Based on the received user input indicating the preference, the controller 10 determines the maximum rate of change of opacity

$\frac{\Delta}{\Delta t}{O_{Max}.}$ In some embodiments, the manufacturer of the vehicle 18 (or any other entity) may prescribe upper and lower limits of the maximum rate of change of opacity

${\frac{\Delta}{\Delta t}O_{Max}},$ which bound the user's adjustment. Likewise, the manufacturer of the vehicle 18 (or any other entity) may prescribe the maximum rate of change of opacity

$\frac{\Delta}{\Delta t}O_{Max}$ itself, such that there is no user customization.

The method 100 continues with operating the visor with the updated optical state (block 180). Particularly, the controller 10 operates the visor 12 to display the updated optical state. In this way, the optical state of the visor 12 reflects the most recently determined sunlight direction [θ_(X) ^(sun), θ_(Y) ^(sun)] and the most recently determined position of the eyes of the driver 16 [X^(left), Y^(left), Z^(left)] and [X^(right), Y^(right), Z^(right)], thereby providing continuous blocking of sunlight from striking the eyes of the driver, but also limiting the rate of change of opacity in each update cycle. After updating the optical state of the visor 12, the method 100 returns to block 120 and begins processing the next image received from the camera 14 in the next update cycle.

Probabilistic Determination of Sunlight Direction

FIG. 6 shows an exemplary method 300 for determining the most likely current sunlight direction [θ_(X) ^(sun), θ_(Y) ^(sun)] in a probabilistic manner using Bayesian Inference. The method 300 begins with defining a plurality of possible sunlight directions and uniformly initializing a probability distribution for the plurality of possible sunlight directions (block 310). Particularly, prior to operation (i.e., prior to initializing the optical state of the visor 12 in block 110 of the method 100), the controller 10 defines a plurality of p possible sunlight directions. As described above, the sunlight direction can be represented by vector that passes through the visor 12 and toward the driver 16 or, more particularly, as pair of angles including the angle at which the sunlight passes through along a first axis (e.g. a horizontal axis) and the angle at which the sunlight passes through along a second axis (e.g., a vertical axis). Moreover, it can be assumed that the eyes of the driver 16 will generally be located within a predetermined region of the cabin 17. Thus, only sunlight directions that also pass through this predetermined region within the cabin 17 need to be considered for operating the visor 12 because only this limited subset of sunlight directions will typically result in sunlight striking the eyes of the driver 16. For example, the predetermined region within the cabin 17 might be defined such that only sunlight angles [θ_(X), θ_(Y)] where −20°<θ_(X)<20° and −10°<θ_(Y)<10° can reasonably be expected to strike the eyes of the driver 16.

The controller 10 predefines the plurality of p possible sunlight directions, which can be thought of as a two-dimensional grid of possible sunlight directions. In one example, the controller 10 defines the p possible sunlight directions in 2° increments across the both the horizontal X-direction and the vertical Y-direction and bounded by predetermined region within the cabin 17 within which the eyes of the driver 16 are expected to be located, resulting in, for example, a 20×10 grid of possible sunlight directions or p=200 possible sunlight directions. Each of the p possible sunlight directions is initialized with a uniform probability lip, such that each of the p possible sunlight directions is assumed to be equally likely at the start of the method 100. The resulting probability distribution can be considered to take the same form as the grid of possible sunlight directions (e.g., a 20×10 grid of probabilities) and collectively add up to 1.0 or 100%. The controller 10 stores the p possible sunlight directions and the associated probabilities in the memory of the controller 10. As will be described in further detail, these probabilities will be continuously updated and refined based on new information, for example using Bayes' Theorem, to arrive at an accurate prediction of the current sunlight direction [θ_(X) ^(sun), θ_(Y) ^(sun)].

The method 300 continues with, for each of a plurality of sample points on the face of the driver, determining (i) an estimated illumination state of the respective sample point and (ii) a certainty of the estimated illumination state (block 320). Particularly, once the current pose of the head of the driver 16 [X^(head), Y^(head), Z^(head)] and [θ_(X) ^(head), θ_(Y) ^(head), θ_(Z) ^(head)] is determined, a defined set of sample points on the face of the driver 16 is continuously tracked in the image(s) of the face of the driver 16. FIG. 7 shows a portion of an exemplary image 60 of the face of the driver 16. A plurality of sample points 62 are defined on the face of the driver 16 according to a predetermined pattern and distribution and at least include sample points in regions of the face around the eyes of the driver 16. In the illustrated embodiment, the sample points 62 are arranged in seven columns in which the five central columns include an equal number of uniformly spaced sample points 62, and in which the left and right most columns include a smaller number of sample points 62. However, it should be appreciated that a wide variety of patterns can be equivalently utilized. As each image is captured, the controller 10 determines the 2D location in the image of each of the sample points based on the current pose of the head of the driver 16 [X^(head), Y^(head), Z^(head)] and [θ_(X) ^(head), θ_(Y) ^(head), θ_(Z) ^(head)]. Particularly, it should be appreciated that the sample points have a defined location on the face of the driver 16 and, thus, when the pose of the head of the driver 16 [X^(head), Y^(head), Z^(head)] and [θ_(X) ^(head), θ_(Y) ^(head), θ_(Z) ^(head)] changes, both the 3D locations of the sample points within the cabin 17 and the 2D locations of the sample points in the images change.

Once the sample points are located in the image, the controller 10 determines an estimated illumination state of each sample point based on the image and based on a previously estimated illumination state for each respective sample point. With reference again to FIG. 7 , as can be seen, a first subset of the sample points 62 are located within in a shadow 52 that has been projected onto the face of the driver 16 by the optical state of the visor 12 and a second subset of the sample points 62 are located within an illuminated region of the face of the driver 16. In the simplest embodiment, the estimated illumination state of each sample point is a binary classification of whether the respective sample point is in a shadow or not in a shadow. However, in further embodiments, the estimated illumination state of each sample point may have more than two possible classifications (e.g., including classifications for intermediate illumination levels). Additionally, in some embodiments, the estimated illumination state of each sample point may be numerical value indicating, in absolute or relative terms, an amount of illumination at the respective sample point in the image.

In at least some embodiments, the controller 10 also determines a certainty of the estimated illumination state of each sample point. Particularly, the shadow detection problem is challenging due to the many variables involved. The face of each driver 16 has a unique skin tone, shape, and size, the shape also varying over time due to different facial expressions of the driver 16. Additionally, the lighting environment that the driver 16 is in is continually changing, with both direct sunlight as well as indirect light bouncing off the objects and environment around the driver 16. As a result, there is a varying degree of uncertainty in determining whether each sample point on the face is in shadow or not. This uncertainty can lead to a noisy estimation of the illumination states, which can result in unnecessary and distracting changes to the optical state of the visor 12. Therefore, it is advantageous to incorporate the uncertainty into a coherent estimation of the illumination state of each sample point.

Returning to FIG. 6 , the method 300 continues with determining a set of plausible sunlight directions as a subset of the plurality of possible sunlight directions (block 330). Particularly, in at least some embodiments, the controller 10 determines a limited set of plausible sunlight directions as a subset of the plurality of p possible sunlight directions using one or more heuristics designed to eliminate possible sunlight directions that are in fact implausible or impossible. In this way, the method 400 advantageously limits the number of possible sunlight directions that must be tested. However, in at least some cases, the controller 10 does not eliminate any of the p possible sunlight directions and the set of plausible sunlight directions simply includes all of the plurality of p possible sunlight directions.

In some embodiments, the controller 10 determines a first bounding box around all of the pixels on the visor 12 that are operated in the opaque optical state and a second bounding box around all of the sample points on the face of the driver 16 that which are classified to be in a shadow. The controller 10 determines which possible sunlight directions would result in an overlap between the first bounding box around the opaque pixels and the second bounding box around the shaded sample points, after projection of the second bounding box onto the visor. If a possible sunlight direction projects the second bounding box around the shaded sample points onto a region of the visor 12 that does not overlap with the first bounding box around the opaque pixels, then that possible sunlight direction is implausible and does not need to be considered. In addition, all possible sunlight directions that project further the second bounding box from the first bounding box can also be excluded. In other words, a particular sunlight direction does not create an overlap between the bounding boxes, it is easily determined that which possible sunlight directions would result in the bounding boxes being even further from one another.

In some embodiments, the controller 10 determines the limited set of plausible sunlight directions as a subset of the plurality of p possible sunlight directions that are within a predetermined range/difference from the estimated sunlight direction of the previous image frame (e.g., only the possible sunlight directions that are within ±5° in the X or Y directions). The predetermined range/difference will generally be a function of the frame rate at which images are captured by the camera 14 and/or processed by the controller 10. Additionally, the predetermined range/difference may further be a function of a rate of rotation of the vehicle 18 during a turning maneuver.

In some embodiments, the controller 10 determines an expected change in the sunlight direction based on previous changes in the estimated sunlight directions over two or more previous image frames. The controller 10 determines the limited set of plausible sunlight directions based on the sunlight direction of the previous image frame and the expected change in the sunlight direction. As an illustrative example, during a turning maneuver of the vehicle 18, the sunlight directions will generally change one way or the other in the horizontal X direction over a sequence of consecutive image frames. Accordingly, if over the course of the previous few frames, the sunlight direction has shifted positively in the horizontal X direction by a threshold amount, it can be assumed that the sunlight direction in the current frame will continue to shift positively in the horizontal X direction or stay the same. Thus, possible sunlight directions representing negative shifts in the horizontal X direction (i.e., the opposite direction of change compared to the previous frames) can be considered implausible.

In some embodiments, the controller 10 is connected to a vehicle computer (not shown) or vehicle sensor (not shown) configured to provide additional contextual information from which changes in the sunlight direction can be inferred, such as a direction of travel, a time of day, acceleration data, steering information, global positioning data, etc. Based on the additional contextual information, the controller 10 eliminates some of the plurality of p possible sunlight directions as being implausible or impossible. In some embodiments, the controller 10 determines an expected change in the sunlight direction based on the additional contextual information and determines the limited set of plausible sunlight directions based on the sunlight direction of the previous image frame and the expected change in the sunlight direction.

The method 300 continues with, for each plausible sunlight direction, projecting the plurality of sample points onto a plane of the visor and determine a likelihood that the respective sunlight direction would result in the estimated illumination states of the plurality of sample points (block 340). Particularly, for each plausible sunlight direction in the limited set of plausible sunlight directions (or, in some cases, each possible sunlight direction in the plurality of p possible sunlight directions), controller 10 projects the sample points on the face of the driver onto a plane/surface of the visor 12 using the respective sunlight direction. As noted above, an estimated illumination state and certainty was determined for each sample point. Thus, the projection of these points onto the plane/surface of the visor 12 results in a set of points in the plane/surface of the visor 12, each point having an estimated illumination state and certainty.

The controller 10 compares the estimated illumination state and certainty of each projected sample point with the optical state of the visor 12 at the time the image was captured. Based on this comparison, the controller 10 determines a likelihood/probability that the current optical state of the visor 12 would have resulted in the estimated illumination states of the sample points. For example, if the sunlight direction used in the projection results in a high correspondence between sample points estimated to be in a shadow and pixels of the visor 12 that are operated in the opaque optical state, then the sunlight direction has a higher likelihood/probability of being correct. Conversely, if the sunlight direction used in the projection results in a low correspondence between sample points estimated to be in a shadow and pixels of the visor 12 that are operated in the opaque optical state, then the sunlight direction has a lower likelihood/probability of being correct.

Once repeated for all of the plausible sunlight directions (or, in some case, all of the p possible sunlight directions), this provides a 2D grid of likelihood/probability estimates in the same form as the grid of possible sunlight directions discussed above (e.g., a 20×10 grid of probabilities). If not done so in their original determination, the controller 10 normalizes the likelihood/probability estimates such that they add up to 1.0 or 100%. Additionally, the controller 10 assigns a very small likelihood/probability estimate to each of the possible sunlight directions that were not tested as a result of being eliminated as being implausible or impossible.

The method 300 continues with updating the probability distribution for the plurality of possible sunlight directions based on the determined likelihoods for each plausible sunlight direction (block 350). Particularly, the controller 10 updates the probability distribution associated with the plurality of p possible sunlight directions, stored in the memory of the controller 10, based on the determined likelihood/probability estimates for the current image. In one embodiment, the controller 10 updates the probability distribution for the plurality of p possible sunlight directions using Bayesian Inference and/or Bayes' Theorem or any other suitable mathematical operation from incorporating new information into a probability estimate. The resulting updated probability distribution takes the same form as the grid of possible sunlight directions discussed above (e.g., a 20×10 grid of probabilities) and adds up to 1.0 or 100%. The controller 10 stores updated probability distribution in the memory of the controller 10. It will be appreciated that the process of estimating the sunlight direction in this manner effectively reduces the effect of the noisy estimation of the illumination states and enables a more stable prediction.

It should be appreciated that the processes of blocks 320, 330, 340, and 350 of the method 300 comprise one exemplary implementation of the process of block 140 in the method 100, in which the current sunlight direction [θ_(X) ^(sun), θ_(Y) ^(sun)] is determined. Thus, once the probability distribution for the current sunlight direction [θ_(X) ^(sun), θ_(Y) ^(sun)] has been determined, the controller 10 proceeds to the process of block 150 in the method 100, as described above.

Embodiments within the scope of the disclosure may also include non-transitory computer-readable storage media or machine-readable medium for carrying or having computer-executable instructions (also referred to as program instructions) or data structures stored thereon. Such non-transitory computer-readable storage media or machine-readable medium may be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such non-transitory computer-readable storage media or machine-readable medium can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code means in the form of computer-executable instructions or data structures. Combinations of the above should also be included within the scope of the non-transitory computer-readable storage media or machine-readable medium.

Computer-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. Computer-executable instructions also include program modules that are executed by computers in stand-alone or network environments. Generally, program modules include routines, programs, objects, components, and data structures, etc. that perform particular tasks or implement particular abstract data types. Computer-executable instructions, associated data structures, and program modules represent examples of the program code means for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps.

While the disclosure has been illustrated and described in detail in the drawings and foregoing description, the same should be considered as illustrative and not restrictive in character. It is understood that only the preferred embodiments have been presented and that all changes, modifications and further applications that come within the spirit of the disclosure are desired to be protected. 

What is claimed is:
 1. A visor system comprising: a camera mounted within an environment and configured to capture a plurality of images of a face of a person in the environment; a visor mounted within the environment and having a plurality of pixels arranged contiguously, an optical state of the visor being adjustable by selectively operating each respective pixel of the plurality of pixels with a respective pixel optical state selected from a plurality of pixel optical states, each pixel optical state in the plurality of pixel optical states having a different opacity such that the respective pixel blocks a different amount of light from passing through a corresponding area of the visor; and a controller operably connected to the camera and to the visor, the controller being configured to receive the plurality of images from the camera and, for each respective image in the plurality of images: determine, based on the respective image, an updated optical state for the visor to block a light source from shining through the visor into eyes of the person, the updated optical state being determined based on a maximum rate of change of opacity such that a change in opacity of the pixel optical state of each pixel in the plurality of pixels in the updated optical state compared to a current optical state of the visor is limited by the maximum rate of change of opacity; and operate the visor to display the updated optical state.
 2. The visor system of claim 1, the controller further configured to, for each respective image in the plurality of images: determine, based on the respective image, (i) a current position of the eyes of the person and (ii) a current light direction at which the light source shines through the visor; and determine, based on the current position of the eyes of the person and the current light direction, the updated optical state for the visor to block the light source from shining through the visor into eyes of the person.
 3. The visor system of claim 1, the controller further configured to, for each respective image in the plurality of images: determine, based on the respective image, a target optical state for the visor to block the light source from shining through the visor into the eyes of the person; determine differences between the target optical state for the visor and the current optical state of the visor; and determine the updated optical state for the visor based on the differences between the target optical state for the visor and the current optical state of the visor.
 4. The visor system of claim 3, the controller further configured to, for each respective image in the plurality of images: determine, based on the respective image, (i) a current position of the eyes of the person and (ii) a current light direction at which the light source shines through the visor; determine a projected eye position on the visor by projecting the current position of the eyes of the person onto the visor using the current light direction; and determine, based on projected eye position on the visor, the target optical state for the visor to block the light source from shining through the visor into the eyes of the person.
 5. The visor system of claim 3, the controller further configured to, for each respective image in the plurality of images, for each respective pixel in the plurality of pixels: determine a difference in opacity between (i) a target pixel optical state for the respective pixel in the target optical state for the visor and (ii) a current pixel optical state of the respective pixel in the current optical state of the visor; and determine an updated pixel optical state for the respective pixel in the updated optical state for the visor based on the difference in opacity between the target pixel optical state the current pixel optical state for the respective pixel.
 6. The visor system of claim 5, the controller further configured to, for each respective image in the plurality of images, for each respective pixel in the plurality of pixels: determine the updated pixel optical state for the respective pixel by changing the opacity of the respective pixel to be closer to the target pixel optical state, the change in opacity of the respective pixel being limited by the maximum rate of change of opacity.
 7. The visor system of claim 5, the controller further configured to, for each respective image in the plurality of images, for each respective pixel in the plurality of pixels: determine the updated pixel optical state for the respective pixel as equal to the current pixel optical state of the respective pixel, in response to the difference in opacity between the target pixel optical state the current pixel optical state for the respective pixel being zero.
 8. The visor system of claim 5, the controller further configured to, for each respective image in the plurality of images, for each respective pixel in the plurality of pixels: determine a maximum change in opacity for updated optical state based on (i) the maximum rate of change of opacity and (ii) a time since a most recent update to optical state of the visor; and determine the updated pixel optical state for the respective pixel as equal to the target pixel optical state of the respective pixel, in response to the difference in opacity between the target pixel optical state the current pixel optical state for the respective pixel being less than the maximum change in opacity.
 9. The visor system of claim 5, the controller further configured to, for each respective image in the plurality of images, for each respective pixel in the plurality of pixels: determine a maximum change in opacity for updated optical state based on (i) the maximum rate of change of opacity and (ii) a time since a most recent update to optical state of the visor; and determine the updated pixel optical state for the respective pixel by adjusting the current pixel optical state of the respective pixel by the maximum change in opacity toward the target pixel optical state, in response to the difference in opacity between the target pixel optical state the current pixel optical state for the respective pixel being greater than the maximum change in opacity.
 10. The visor system of claim 5, the controller further configured to, for each respective image in the plurality of images, for each respective pixel in the plurality of pixels: determine the maximum rate of change of opacity for the respective pixel based on a location of the respective pixel in the visor, wherein the maximum rate of change of opacity is defined as a function of the location of the respective pixel in the visor.
 11. The visor system of claim 10, wherein the maximum rate of change of opacity is defined as a function of the location of the respective pixel in the visor such that (i) pixels that are located relatively closer to a center of the visor have relatively higher maximum rate of change of opacity and (ii) pixels that are located relatively further from the center of the visor have relatively lower maximum rate of change of opacity.
 12. The visor system of claim 1, the controller further configured to, for each respective image in the plurality of images: determine, based on the respective image, the updated optical state for the visor, a positive change in opacity of the pixel optical state of each pixel in the plurality of pixels in the updated optical state compared to the current optical state of the visor being limited by a maximum positive rate of change of opacity, a negative change in opacity of the pixel optical state of each pixel in the plurality of pixels in the updated optical state compared to the current optical state of the visor being limited by a maximum negative rate of change of opacity.
 13. The visor system of claim 12, wherein a magnitude of the maximum positive rate of change of opacity is higher than a magnitude of the maximum negative rate of change of opacity.
 14. The visor system of claim 1, the controller further configured to, for each respective image in the plurality of images: determine, based on the respective image, a current position of the eyes of the person; and determine the maximum rate of change of opacity based on at least one of (i) the current position of the eyes and (ii) a rate of change of the current position of the eyes.
 15. The visor system of claim 1, the controller further configured to, for each respective image in the plurality of images: determine, based on the respective image, a current light direction at which the light source shines through the visor; and determine the maximum rate of change of opacity based on at least one of (i) the current light direction and (ii) a rate of change of the current light direction.
 16. The visor system of claim 1, the controller further configured to: receive a user input provided via a user interface; and determine the maximum rate of change of opacity based on the user input.
 17. The visor system of claim 1, wherein each respective pixel optical state in the plurality of pixel optical states is characterized by a numerical value that represents a respective opacity of the respective pixel optical state.
 18. The visor system of claim 1, wherein the visor includes a liquid crystal display (LCD) panel and each pixel in the plurality of pixels is an LCD pixel.
 19. A method for operating a visor system, the visor system including a visor mounted within an environment and having a plurality of pixels arranged contiguously, an optical state of the visor being adjustable by selectively operating each respective pixel of the plurality of pixels with a respective pixel optical state selected from a plurality of pixel optical states, each pixel optical state in the plurality of pixel optical states having a different opacity such that the respective pixel blocks a different amount of light from passing through a corresponding area of the visor, the method comprising: capturing, with a camera mounted within the environment, a plurality of images of a face of a person in the environment; determining a maximum rate of change of opacity; and for each respective image in the plurality of images: determining, with a controller, based on the respective image, an updated optical state for the visor to block a light source from shining through the visor into eyes of the person, the updated optical state being determined based on the maximum rate of change of opacity such that a change in opacity of the pixel optical state of each pixel in the plurality of pixels in the updated optical state compared to a current optical state of the visor is limited by the maximum rate of change of opacity; and displaying, with the visor, the updated optical state.
 20. A non-transitory computer-readable medium for operating a visor system, the visor system including (i) a camera mounted within an environment and configured to capture a plurality of images of a face of a person in the environment and (ii) a visor mounted within the environment and having a plurality of pixels arranged contiguously, an optical state of the visor being adjustable by selectively operating each respective pixel of the plurality of pixels with a respective pixel optical state selected from a plurality of pixel optical states, each pixel optical state in the plurality of pixel optical states having a different opacity such that the respective pixel blocks a different amount of light from passing through a corresponding area of the visor, the computer-readable medium storing program instructions that, when executed by a processor, cause the processor to: receive the plurality of images from the camera; and for each respective image in the plurality of images: determine, based on the respective image, an updated optical state for the visor to block a light source from shining through the visor into eyes of the person, the updated optical state being determined based on a maximum rate of change of opacity such that a change in opacity of the pixel optical state of each pixel in the plurality of pixels in the updated optical state compared to a current optical state of the visor is limited by the maximum rate of change of opacity; and operate the visor to display the updated optical state. 